TRGC1 and Cowden disease: However, if patients have increased serum TG2-IgA titers and increased density of TCRγ/δ+ intraepithelial T cells7,8, with or without detectable submucosal IgA-TG2 immune complexes, they would be classified as having CD in which the degree of intestinal villous atrophy would depend on the amount of gluten consumed.